Lake Reflections
Tso Moriri Lake, India

Most objects do not emit light. Rather, they reflect it from a source like a light bulb or sunlight. This common process allows us to see these things that are all around us. In fact, one of the fundamental laws of the physics of light involves reflection. Reflection consists of two rays: an incoming or 'incident' ray and an outgoing or 'reflected' ray. All reflected light obeys the rule that says the incident ray strikes a surface at the same angle that the reflected ray bounces away from it. In the case of a smooth surface like a mirror or, in the case of the photograph, the calm top of a lake, a clear identical image is produced.